Hi all!

I'm trying to make a simple channel indicator, the upper line calculates as a highest high of 12-period Bid price array and the bottom line = the lowest low of 12-period Ask price array.

But when I'm trying to compile it the error appears with a messge "OfferSide cannot be resolved".
And the same with the AppliedPrice.

What is wrong with the code?
And how can I manage this problem?

Thank you in advance!

package jforex;

import com.dukascopy.api.indicators.*;

public class Channel2Lines_v2 implements IIndicator {
    private IndicatorInfo indicatorInfo;
    private InputParameterInfo[] inputParameterInfos;
    private OptInputParameterInfo[] optInputParameterInfos;
    private OutputParameterInfo[] outputParameterInfos;
    private double[][] inputs = new double[2][];
    private int timePeriod = 12;
    private double[][] outputs = new double[2][];
    
    public void onStart(IIndicatorContext context) {
        indicatorInfo = new IndicatorInfo("ChannelInd", "Calculates extremums", "My indicators",
                true, false, false, 2, 1, 2);
        inputParameterInfos = new InputParameterInfo[] {
        new InputParameterInfo("Ch1_Price:", InputParameterInfo.Type.PRICE){
            {
                setAppliedPrice(AppliedPrice.HIGH);
                setOfferSide(OfferSide.BID);
            }
        },
        new InputParameterInfo("Ch2_Price:", InputParameterInfo.Type.PRICE){
            {
                setAppliedPrice(AppliedPrice.LOW);
                setOfferSide(OfferSide.ASK);
            }
        }
        
        };
        optInputParameterInfos = new OptInputParameterInfo[] {new OptInputParameterInfo("Time period", OptInputParameterInfo.Type.OTHER,
                new IntegerRangeDescription(12, 2, 100, 1))};
        outputParameterInfos = new OutputParameterInfo[] {new OutputParameterInfo("Channel1", OutputParameterInfo.Type.DOUBLE,
                OutputParameterInfo.DrawingStyle.LINE),
                new OutputParameterInfo("Channel2", OutputParameterInfo.Type.DOUBLE,OutputParameterInfo.DrawingStyle.LINE)};
    }

    public IndicatorResult calculate(int startIndex, int endIndex) {
        //calculating startIndex taking into account lookback value
        if (startIndex - getLookback() < 0) {
            startIndex -= startIndex - getLookback();
        }
        int i, j;
        for (i = startIndex, j = 0; i <= endIndex; i++, j++) {
            double value1 = 0;
            double value2 = 99999;
            for (int k = timePeriod; k > 0; k--) {
                if (inputs[0][i - k] > value1)
                    value1 = inputs[0][i - k];
                if (inputs[1][i - k] < value2)
                    value2 = inputs[1][i - k];
            }
            outputs[0][j] = value1;
            outputs[1][j] = value2;
        }
        return new IndicatorResult(startIndex, j);
    }

    public IndicatorInfo getIndicatorInfo() {
        return indicatorInfo;
    }

    public InputParameterInfo getInputParameterInfo(int index) {
        if (index <= inputParameterInfos.length) {
            return inputParameterInfos[index];
        }
        return null;
    }

    public int getLookback() {
        return timePeriod;
    }

    public int getLookforward() {
        return 0;
    }

    public OptInputParameterInfo getOptInputParameterInfo(int index) {
        if (index <= optInputParameterInfos.length) {
            return optInputParameterInfos[index];
        }
        return null;
    }

    public OutputParameterInfo getOutputParameterInfo(int index) {
        if (index <= outputParameterInfos.length) {
            return outputParameterInfos[index];
        }
        return null;
    }

    public void setInputParameter(int index, Object array) {
        inputs[index] = (double[]) array;
    }

    public void setOptInputParameter(int index, Object value) {
        timePeriod = (Integer) value;
    }

    public void setOutputParameter(int index, Object array) {
        outputs[index] = (double[]) array;
    }
}

API Support, thank you!

The code had compiled successfully.
But when I add indicator to the chart, the new error occures:

19:28:36 Error in indicator: java.lang.ClassCastException: [[D cannot be cast to [D @ jforex.Channel2Lines_v21.setInputParameter(Channel2Lines_v21.java:97)

Full Exeption:

java.lang.ClassCastException: [[D cannot be cast to [D
at jforex.Channel2Lines_v21.setInputParameter(Channel2Lines_v21.java:97)
at com.dukascopy.api.impl.cm.a(Unknown Source)
at com.dukascopy.charts.math.dataprovider.AbstractDataProvider$e.c(Unknown Source)
at com.dukascopy.charts.math.dataprovider.AbstractDataProvider$e.run(Unknown Source)

What do I have to do with inputs?

    public void setInputParameter(int index, Object array) {
        inputs[index] = (double[]) array;
    }

Change the InputParameterInfo to InputParameterInfo.Type.DOUBLE.

It works fine now, thank you!

The only issue is when the indicator is placed on the chart, sometimes the error appears:
18:20:03 Error in indicator: java.lang.ArrayIndexOutOfBoundsException: 21 @ jforex.Channel2Lines_v21.calculate(Channel2Lines_v21.java:54)

Full exeption:
java.lang.ArrayIndexOutOfBoundsException: 21
at jforex.Channel2Lines_v21.calculate(Channel2Lines_v21.java:54)
at com.dukascopy.api.impl.cm.a(Unknown Source)
at com.dukascopy.charts.math.dataprovider.AbstractDataProvider$e.c(Unknown Source)
at com.dukascopy.charts.math.dataprovider.AbstractDataProvider$e.run(Unknown Source)

But still, despite that, indicator works correctly, so it's not a big problem.

The final code is:

package jforex;

import com.dukascopy.api.indicators.*;
import com.dukascopy.api.IIndicators.AppliedPrice;
import com.dukascopy.api.OfferSide;

public class Channel2Lines_v21 implements IIndicator {
    private IndicatorInfo indicatorInfo;
    private InputParameterInfo[] inputParameterInfos;
    private OptInputParameterInfo[] optInputParameterInfos;
    private OutputParameterInfo[] outputParameterInfos;
    private double[][] inputs = new double[2][];
    private int timePeriod = 12;
    private double[][] outputs = new double[2][];
    
    public void onStart(IIndicatorContext context) {
        indicatorInfo = new IndicatorInfo("ChannelInd", "Calculates extremums", "My indicators",
                true, false, false, 2, 1, 2);
        inputParameterInfos = new InputParameterInfo[] {
        new InputParameterInfo("Ch1_Price:", InputParameterInfo.Type.DOUBLE){
          {
           setAppliedPrice(AppliedPrice.HIGH);
           setOfferSide(OfferSide.BID);  
          }
        },
        new InputParameterInfo("Ch2_Price:", InputParameterInfo.Type.DOUBLE){
            {
             setAppliedPrice(AppliedPrice.LOW);
             setOfferSide(OfferSide.ASK);
            }
        }
        
        };
        
        optInputParameterInfos = new OptInputParameterInfo[] {new OptInputParameterInfo("Time period", OptInputParameterInfo.Type.OTHER,
                new IntegerRangeDescription(12, 2, 100, 1))};
        outputParameterInfos = new OutputParameterInfo[] {new OutputParameterInfo("Channel1", OutputParameterInfo.Type.DOUBLE,
                OutputParameterInfo.DrawingStyle.LINE),
                new OutputParameterInfo("Channel2", OutputParameterInfo.Type.DOUBLE,OutputParameterInfo.DrawingStyle.LINE)};
    }

    public IndicatorResult calculate(int startIndex, int endIndex) {
        //calculating startIndex taking into account lookback value
        if (startIndex - getLookback() < 0) {
            startIndex -= startIndex - getLookback();
        }
        int i, j;
        for (i = startIndex, j = 0; i <= endIndex; i++, j++) {
            double value1 = 0;
            double value2 = 999;
            for (int k = timePeriod; k > 0; k--) {
                if (inputs[0][i - k] > value1)
                    value1 = inputs[0][i - k];
                if (inputs[1][i - k] < value2)
                    value2 = inputs[1][i - k];
            }
            outputs[0][j] = value1;
            outputs[1][j] = value2;
        }
        return new IndicatorResult(startIndex, j);
    }

    public IndicatorInfo getIndicatorInfo() {
        return indicatorInfo;
    }

    public InputParameterInfo getInputParameterInfo(int index) {
        if (index <= inputParameterInfos.length) {
            return inputParameterInfos[index];
        }
        return null;
    }

    public int getLookback() {
        return timePeriod;
    }

    public int getLookforward() {
        return 0;
    }

    public OptInputParameterInfo getOptInputParameterInfo(int index) {
        if (index <= optInputParameterInfos.length) {
            return optInputParameterInfos[index];
        }
        return null;
    }

    public OutputParameterInfo getOutputParameterInfo(int index) {
        if (index <= outputParameterInfos.length) {
            return outputParameterInfos[index];
        }
        return null;
    }

    public void setInputParameter(int index, Object array) {
        inputs[index] = (double[]) array;
    }

    public void setOptInputParameter(int index, Object value) {
        timePeriod = (Integer) value;
    }

    public void setOutputParameter(int index, Object array) {
        outputs[index] = (double[]) array;
    }
}

Consider adding additional array range checks:

            for (int k = timePeriod; k > 0 && i - k < inputs[0].length && i - k < inputs[1].length; k--) {

It looks like the error is gone.
Thanks again!